Olefin polymerization catalyst system producing polymer with low active chloride

ABSTRACT

A catalyst system especially suited for polymerizing alpha-olefins in the gas-phase to polymers containing essentially no active chloride comprises (A) a titanium-containing component supported on a hydrocarbon-insoluble magnesium-containing compound in combination with an electron donor compound and (B) a co-catalyst comprising (a) at least one trialkylaluminum compound (b) an aromatic acid ester and (c) an unhindered secondary amine, optionally reacted with a dialkylaluminum hydride, in substantial absence of compounds containing an Al-Cl bond.

BACKGROUND OF THE INVENTION

This invention relates to olefin polymerization catalysts and moreparticularly relates to use of supported propylene polymerizationcatalysts in gas-phase polymerization in combination with achloride-free co-catalyst system.

Gas-phase polymerization of olefins, especially propylene, has become anattractive commercial process. In gas-phase polymerization, gaseousolefin monomer is contacted with a catalyst system to form solid polymerwithout solvent or diluent. Catalyst systems useful in gas-phasepolymerization must be very active. Because the forming polymer is notin contact with a solvent or diluent, such as paraffinic hydrocarbon,there is no inherent removal of hydrocarbon-soluble polymer productssuch as amorphous or atactic material. Therefore, catalyst systems usedin gas-phase polymerization also must produce relatively low amounts ofsuch amorphous or atactic material.

Typically, polymer produced from a gas-phase reactor is in the form of adry powder. Sometimes it is advisable to treat such powder with aflowing gas-stream such as nitrogen containing a catalyst deactivationagent such as water, air, oxygen, alcohol, ammonium compounds, carbonoxides and the like to deactivate catalyst residues remaining in apolymer powder. If substantial amounts of corrosive catalyst residuesremain in the powder, expensive stabilization agents must beincorporated within the polymer to avoid corrosion of fabricationequipment. Chlorine compounds in polymers such as polypropylene arenoted as creating corrosivity problems. Although all chlorine compoundsdo not exhibit the same corrosivity problems, a test for "activechloride" shows levels of chlorine-containing compounds which areassociated with corrosivity. A common component in olefin polymerizationcatalyst systems are alkyl aluminum chlorides such as diethylaluminumchloride. A method to avoid active chloride is to minimize, orpreferably eliminate, incorporation as such alkylaluminum chlorides incatalyst systems.

As noted above, gas-phase polymerization systems show considerablecommercial advantage. However, it has been found that catalyst systemsgenerally useful for slurry or bulk polymerization may not be usedsuccessfully in gas-phase polymerizations. The present inventiondemonstrates this fact. Olefin polymerization using atitanium-containing compound in combination with alkylaluminum compoundsare well known as Ziegler-Natta catalysts. There are many variations ofthis concept in the art with a variety of forms of titanium compounds,alkylaluminum compounds and many varieties of modifiers and promoterpackages. Various titanium compounds supported on magnesium-containingcompounds have been reported including U.S. Pat. Nos. 3,901,863 and4,227,370, all incorporated by reference herein.

Co-catalysts incorporating secondary amines have been disclosed incertain contexts. For example, U.S. Pat. Nos. 4,094,818, 4,224,181 and4,224,182 describe the use of hindered amine compounds such as2,2,6,6-tetramethylpiperidine as one component in a cocatalyst system.U.S. Pat. Nos. 4,431,570, 4,431,571 and 4,431,572, all incorporated byreference herein, describe catalyst systems in which comminutedsupported titanium-containing catalyst component is retreated with amixture containing a titanium halide, at least one organic acid esterand, optionally, a chlorocarbon or a haloalkylchlorosilane.

Olefin polymerization catalysts, especially propylene polymerizationcatalysts, supported on a magnesium-containing compound and containingan electron donor compound such as an alkyl aromatic acid ester havebeen described widely.

SUMMARY OF THE INVENTION

A catalyst system especially suited for polymerizing alpha-olefins inthe gas-phase to polymers containing essentially no active chloridecomprises (A) a titanium-containing component supported on ahydrocarbon-insoluble magnesium-containing compound in combination withan electron donor compound and (B) a co-catalyst comprising (a) at leastone trialkylaluminum compound (b) an aromatic acid ester and (c) anunhindered secondary amine, optionally reacted with a dialkylaluminumhydride, in substantial absence of compounds containing an Al--Cl bond.

BRIEF DESCRIPTION OF THE INVENTION

The invention described herein involves the co-catalyst component of aZiegler-Natta olefin polymerization catalyst system. Typically, atitanium-containing component is introduced into a polymerizationreaction together with co-catalyst component comprising an alkylaluminumcompound and selected modifier compounds. This invention is directed toa co-catalyst component system which can be used with a supportedtitanium-containing component which does not introduce active chloridespecies into resulting polymer while maintaining high activity andacceptable levels of amorphous polymer production. The catalyst systemdescribed herein especially is useful in gas-phase olefin polymerizationsystems which retain amorphous polymer and active chloride species inpolymer produced with minimal deactivation procedures. It has been foundthat catalysts prepared according to this invention polymerizealpha-olefins, specifically propylene, to highly crystalline polymerwith essentially no active chloride species.

The co-catalysts of this invention are based on three components incombination. A trialkylaluminum is combined with an alkyl aromatic acidester and an alkyl unhindered secondary amine or a secondary aminereacted with dialkylaluminum hydride.

Unhindered aliphatic secondary amines useful in this invention includethose with a formula RR¹ NH wherein R and R¹ are the same or differentalkyl groups containing from two to about eight carbon atoms, which, ifbranched, contain no more than one methyl group attached to the carbonatom adjacent to the nitrogen atom. Aromatic amines are not included inamines useful in this invention. It is contemplated also that thisformula includes cyclic secondary amines containing four to about tencarbon atoms. Specific examples of unhindered secondary amine includepiperidine, 2-methyl piperidine, 4-ethyl piperidine, 3,5-dimethylpiperidine, pyrrolidine, homopiperidine, piperazine, 2-methylpyrrolidine, diethyl amine, di-n-propylamine, dicyclohexylamine,ethylpropylamine, ethyl-s-butylamine and the like. Cyclic unhinderedsecondary amines are preferred wherein there is no more than one methylgroup on a carbon adjacent to a nitrogen atom. More preferred are cyclicamines with no alkyl substituents such as piperidine, pyrrolidine,homopiperidine and piperazine. Piperidine is the most preferred.

In another aspect of this invention, the above-described unhinderedsecondary amines may be reacted with a dialkylaluminum hydride such asdiisopropylaluminium hydride. Typically, suitable dialkylaluminumhydrides contain alkyl groups having from about two to about six carbonatoms such as diethylaluminum hydride or di-n-butyl aluminum hydride.Diisobutylaluminum hydride is preferred. Generally, such anamine-aluminum hydride reaction product is prepared by combiningapproximately equimolar amounts of each component typically in an inertdiluent such as a paraffinic hydrocarbon. The resulting reaction productmay be used in further preparation of a co-catalyst without separationor purification of the product.

Co-catalysts of this invention include a trialkylaluminum with a formulaRR'R"Al wherein R, R', R" are alkyl groups contain from two to about sixcarbon atoms. Examples of such trialkylaluminum includetri-n-butylaluminum, tri-isobutylaluminum, tri-s-butylaluminum,tri-n-pentylaluminum, tri-iso-pentylaluminum, and tri-hexylaluminum.Mixtures of trialkylaluminums can be used. Preferred trialkylaluminumsinclude triethylaluminum, triisobutylaluminum and a combination thereof.The most preferred trialkylaluminum is a combination of triethylaluminumand triisobutylaluminum.

Use of the co-catalyst system of this invention in polymerization of analpha-olefin such as propylene yields a polymer which generally containsessentially no active chloride even though chloride in some form may bepresent. Such non-active chloride may be introduced through thesupported titanium-containing component. In order to preserve the lackof active chloride in the polymer, compounds containing an Al--Cl bondshould be avoided during polymerization. Active Chloride is measured asthe amount of hydrogen chloride gas evolved while passing a stream ofnitrogen over a molten polypropylene sample at 300° C. in parts permillion by weight (ppm). Typically, "active chloride" determinations arerun in duplicate or triplicate with each measurement reportedindividually. It is contemplated that polymer containing essentially no"active chloride" contains less than 20 ppm, preferably less than 10ppm, "active chloride."

Applicants believe that addition of the unhindered secondary amineaccording to this invention suppresses ester alkylation and reduction,which is most pronounced in a solventless system such as gas-phasepolymerization. In addition, use of such amines according to thisinvention is believed to promote improved polymer stability. Since theco-catalyst is dispersed uniformly in the polymeric material, a moreeven distribution of such stabilization effect should be observed.

In the cocatalyst composition of this invention, the trialkylaluminumcompound is employed in at least an amount which is effective to promotethe polymerization activity of the supported component. Preferably theratio of moles of trialkylaluminum component to gram-atom of titanium inthe supported component is at least about 3:1. More preferably, thisratio ranges from about 50:1 to about 500:1, and typically about 100:1to about 300:1 although substantially greater amounts of alkylaluminumcomponent also can be used with desirable results.

The molar ratio of trialkylaluminum to aromatic ester compound in thecocatalyst typically may vary from about 1.0 to about 10, preferablyfrom about 2.5 to about 4.5. The molar ratio of unhindered secondaryamine to alkylaluminum compound useful in the co-catalyst of thisinvention may vary from about 1.0 to about 0.1, preferably from about0.75 to about 0.25.

Titanium-containing components useful in this invention generally aresupported on hydrocarbon-insoluble, magnesium-containing compounds incombination with an electron donor compound. Such supportedtitanium-containing olefin polymerization catalyst component typicallyis formed by reacting a titanium(IV) halide, an electron donor compoundand a hydrocarbon-insoluble magnesium-containing compound. Optionally,such supported titanium-containing reaction product may be furthertreated or modified by comminution or further chemical treatment withadditional electron donor or Lewis acid species.

Suitable hydrocarbon-insoluble, magnesium-containing compounds can be amagnesium halide; a reaction product of a magnesium halide such asmagnesium chloride or magnesium bromide, with an organic compound, suchas an alcohol or an organic acid ester or with an organometalliccompound of metals of Groups I-III. A preferable magnesium-containingcompound is based on at least one magnesium alcoholate which may bepretreated with at least one modifier such as mineral acid or anhydridesof sulfur, organometallic, chalcogenide derivative of hydrogen sulfide,and organic acids and esters thereof. Such magnesium-containing compoundmay be the pretreatment product of at least one magnesium alcoholate, atleast one Group II or IIIA metal alkyl and, optionally, at least onemodifier such as a mineral acid or an anhydride, sulfur, organometallicchalcogenide derivatives of hydrogen sulfide, organic acids and organicacid esters.

Organic electron donors useful in preparation of stereospecificsupported catalyst components can be organic compounds containing one ormore atoms of oxygen, nitrogen, sulfur and phosphorus. Such compoundsinclude organic acids, organic acid esters, alcohols, ethers, aldehydes,ketones, amines, amine oxides, amides, thiols and various phosphorousacid esters and amides and like. Mixtures of organic electron donors canbe used if desired. Suitable nitrogen-containing compounds includeamines such as piperidine and 2,2,6,6-tetramethylpiperidine. Specificexamples of useful oxygen-containing electron donor compounds includeorganic acids and esters. These compounds also can be used to pretreat amagnesium-containing component. Useful organic acids contain from 1 toabout 20 carbon atoms and 1 to about 4 carboxyl groups.

Titanium(IV) compounds useful in preparation of the stereospecificsupported catalyst components of this invention are titanium halides andhaloalcoholates having 1 to about 20 carbon atoms per alcoholate group.Mixtures of titanium compounds can be employed if desired.

Preferred titanium compounds are the halides and haloalcoholates having1 to about 8 carbon atoms per alcoholate group. Examples of suchcompounds include TiCl₄, TiBr₄, Ti(OCH₃)Cl₃, Ti(OC₂ H₅)Cl₃, Ti(OC₄H₉)Cl₃, Ti(OC₆ H₅)Cl₃, Ti(OC₆ H₁₃)Br₃, Ti(OC₈ H₁₇)Cl₃, Ti(OCH₃)₂ Br₂,Ti(OC₂ H₅)₂ Cl₂, Ti(OC₆ H₁₃)₂ Cl₂, Ti(OC₈ H₁₇)₂ Br₂, Ti(OCH₃)₃ Br,Ti(OC₂ H₅)₃ Cl, Ti(OC₄ H₉)₃ Cl, Ti(OC₆ H₁₃)₃ Br, and Ti(OC₈ H₁₇)₃ Cl.Titanium tetrahalides, particularly titanium tetrachloride (TiCl₄), aremost preferred.

From the standpoint of catalyst performance and preparative ease, theorganic electron donors which are preferred according to this inventionare C₁ -C₆ alkyl esters of aromatic monocarboxylic acids and halogen-,hydroxyl-, oxo-, alkyl-, alkoxy-, aryl-, and aryloxy-substitutedaromatic monocarboxylic acids. The preferred electron donor compoundsinclude esters of aromatic acids. Among these, the alkyl esters ofbenzoic and halobenzoic acids wherein the alkyl group contains 1 toabout 6 carbon atoms, such as methyl benzoate, methyl bromobenzoate,ethyl benzoate, ethyl chlorobenzoate, ethyl bromobenzoate, butylbenzoate, isobutyl benzoate, hexyl benzoate, and cyclohexyl benzoate,are particularly preferred. Other preferred esters include ethylanisate, methyl p-toluate and dialkylphthalate esters such asdiisobutylphthalate.

In preparation of the stereospecific supported catalyst components ofthis invention, typically, the magnesium-containing product,titanium(IV) component, and organic electron donor component arecontacted in amounts such that the atomic ratio of titanium to metal inthe magnesium-containing component employed in pretreatment is at leastabout 0.5:1. Preferably, this ratio ranges from about 0.5:1 to about20:1 and more preferably, from about 2:1 to about 15:1. The electrondonor component is used in an amount ranging from about 0.001 to about1.0 mole per gram atom of titanium, and preferably from about 0.005 toabout 0.6 mole per gram atom. Best results are achieved when this ratioranges from about 0.01 to about 0.3 mole per gram atom of titanium.

The sequence in which the components are contacted may be varied.Suitably, magnesium-containing product, titanium(IV) component, andelectron donor component are contacted concurrently or two of thecomponents are contacted followed by addition of the remainingcomponent. From the standpoint of catalyst performance and preparativeease, the preferred preparative sequence is to combine themagnesium-containing product and titanium(IV) component and then add theorganic electron donor component to the result.

The magnesium-containing product, titanium(IV), and electron donorcomponents preferably are contacted in the presence of an inerthydrocarbon or halogenated hydrocarbon diluent, although other suitabletechniques can be employed. Examples of suitable diluents includehexane, heptane, nonane, toluene, xylene, 1,1,2-trichloroethane,1,2-dichloroethane and carbon tetrachloride.

Reaction between the magnesium-containing product, titanium component,and organic electron donor is carried out at temperatures ranging fromabout 50° to about 170° C. Best results are obtained at about 90° toabout 130° C. Generally the reaction is carried out over a period ofseveral minutes to several hours, with about 1/2 to about 10 hoursgiving good results at economical rates. Most preferably, the reactiontime ranges from about 1 to about 5 hours. When the components employedin preparation of the invented catalyst components are contactedaccording to the preferred preparative sequence, best results areattained when the magnesium-containing product and titanium(IV)component are combined at about ambient temperature followed by additionof electron donor, at about ambient temperature and with agitation, overabout 1/4 to about 11/2 hours and then heating at about 90° to about130° C. for about 1/2 to about 3 hours with continued agitation.

In addition, the reaction mixture of the magnesium-containing product,titanium component and electron donor can contain an organochlorosilanein a concentration up to about 80 mole % based upon titanium.

A magnesium-containing product useful in catalysts in this inventionpreferably is obtained by contacting pretreatment components comprising(a) at least one magnesium alcoholate of the formula Mg(OR¹)_(n)(OR²)_(2-n) wherein R¹ and R² are identical or different hydrocarbylradicals of 1 to about 20 carbon atoms and n ranges from 0 to 2; and (b)at least one Group II or IIIA metal alkyl containing 1 to about 20carbon atoms per alkyl radical.

The pretreatment components optionally may include at least one modifierselected from the group consisting of mineral acids and anhydrides ofsulfur, organometallic chalcogenide derivatives of hydrogen sulfide,organic acids and esters thereof.

Specific examples of magnesium alcoholates which are useful in forming apretreated magnesium-containing component useful in this inventioninclude Mg(OCH₃)₂, Mg(OC₂ H₅)₂, Mg(OC₄ H₉)₂, Mg(OC₆ H₅)₂, Mg(OC₆ H₁₃)₂,Mg(OC₉ H₁₉)₂, Mg(OC₁₀ H₇)₂, Mg(OC₁₂ H₉)₂, Mg(OC₁₂ H₂₅)₂, Mg(OC₁₆ H₃₃)₂,Mg(OC₂₀ H₄₁)₂, Mg(OCH₃)(OC₂ H₅), Mg(OCH₃)(OC₆ H₁₃), Mg(OC₂ H₅)(OC₈ H₁₇),Mg(OC₆ H₁₃)(OC₂₀ H₄₁), Mg(OC₃ H₇)(OC₁₀ H₇), and Mg(OC₁₆ H₃₃)(OC₁₈ H₃₇).Mixtures of magnesium alcoholates also can be employed if desired.Additionally, although not preferred, mixtures of magnesium alcoholateswith minor amounts of other suitable metal salts such as alcoholates oflanthanum and the lanthanide metals, magnesium halides, hydroxyhalides,carboxylates, and so forth can be used.

Preferred magnesium alcoholates useful in catalysts in this inventionhave the formula Mg(OR¹)₂ wherein R¹ is an alkyl radical of 1 to about 6carbon atoms, an aryl radical of 6 to about 12 carbon atoms or analkaryl or aralkyl radical of 6 to about 12 carbon atoms. Use ofmagnesium ethoxide is preferred. Magnesium hydrocarbyl carbonates alsocan be used.

Preferred Group II and IIIA metal alkyls are those of magnesium, zinc,and aluminum wherein the alkyl radicals contain 1 to about 12 carbonatoms. Trialkylaluminums containing 1 to about 6 carbon atoms per alkylradical, such as triethylaluminum and triisobutylaluminum are used.

The pretreated magnesium-containing component is obtained by contactingcomponents comprising at least one magnesium alcoholate and at least oneGroup II or IIIA metal alkyl. The components are employed in amountssuch that the atomic ratio of metal in the Group II or IIIA metal alkylcomponent to metal in the magnesium alcoholate component ranges fromabout 0.001:1 to about 1:1. Preferably, this ratio ranges from about0.005:1 to about 0.5:1. If a pretreatment modifier is used, the amountof such modifier ranges from about 0.001 to about 2 moles ofpretreatment modifier per mole of Group II or IIIA metal alkylcomponent, preferably, from about 0.005:1 to about 1:1, and particularlyfrom about 0.01:1 to about 0.5:1.

Diluents suitable for use in pretreatment include hydrocarbons andhalogenated derivatives thereof that are substantially inert to thepretreatment components employed and, preferably, are liquid atpretreatment temperatures. Examples of useful diluents include alkanessuch as hexane, cyclohexane, ethylcyclohexane, heptane, octane, nonane,decane, undecane, and so forth; aromatics such as xylenes andethylbenzene; and halogenated and hydrogenated aromatics such aschlorobenzene, o-dichlorobenzene, tetrahydronaphthalene, anddecahydronaphthalene. Preferred diluents are the alkanes and especiallyhexane. Optionally, all or part of the pretreatment may be conducted inthe presence of one or more alpha-olefins which, when introduced intothe preparative system in gaseous form, can serve to exclude catalystpoisons. The presence of one or more alpha-olefins during pretreatmentalso can result in improved stereospecificity. Useful alpha-olefinsinclude ethylene, propylene, butene-1, pentene-1, 4-methylpentene-1,hexene-1, and mixtures thereof. Of course, any alpha-olefin employedduring pretreatment should be of relatively high purity, for example,polymerization grade or higher. Other precautions which aid in excludingpoisons include purification of any diluent to be employed, such as bypercolation through molecular sieves and/or silica gel prior to use, anddrying and/or heating of magnesium alcoholate pretreatment components.

As a result of the pretreatment, there is obtained ahydrocarbon-insoluble, magnesium-containing pretreatment product whichcan be reacted with at least one halogen-containing titanium(IV)compound and at least one organic electron donor to form astereospecific supported catalyst component especially useful in thestereospecific polymerization of alpha-olefins of 3 or more carbonatoms.

Due to the sensitivity of catalyst components to catalyst poisons suchas water, oxygen, and carbon oxides, the catalyst components areprepared in the substantial absence of such materials. Catalyst poisonscan be excluded by carrying out the preparation under an atmosphere ofan inert gas such as nitrogen or argon, or an atmosphere ofalpha-olefin. As noted above, purification of any diluent to be employedalso aids in removing poisons from the preparative system.

As a result of the above-described preparation there is obtained a solidreaction product suitable for use as a catalyst component. Prior to suchuse, it is desirable to remove incompletely-reacted starting materialsfrom the solid reaction product. This is conveniently accomplished bywashing the solid, after separation from any preparative diluent, with asuitable solvent, such as a liquid hydrocarbon or chlorocarbon,preferably within a short time after completion of the preparativereaction because prolonged contact between the catalyst component andunreacted starting materials may adversely affect catalyst componentperformance.

Although not required, the solid reaction product prepared as describedherein may be contacted with at least one liquid Lewis acid prior topolymerization. Such Lewis acids useful according to this invention arematerials which are liquid at treatment temperatures and have a Lewisacidity high enough to remove impurities such as unreacted startingmaterials and poorly affixed compounds from the surface of theabove-described solid reaction product. Preferred Lewis acids includehalides of Group III-V metals which are in the liquid state attemperatures up to about 170° C. Specific examples of such materialsinclude BCl₃, AlBr₃, TiCl₄, TiBr₄, SiCl₄, GeCl₄, SnCl₄, PCl₃ and SbCl₅.Preferable Lewis acids are TiCl₄ and SiCl₄. Mixtures of Lewis acids canbe employed if desired.

Although not required, the above-described solid reaction product may bewashed with an inert liquid hydrocarbon or halogenated hydrocarbonbefore contact with a Lewis acid. Suitable inert liquids include thoseidentified hereinabove as pretreatment and preparative diluents. If sucha wash is conducted it is preferred to substantially remove the inertliquid prior to contacting the washed solid with Lewis acid.

The liquid Lewis acid employed according to the invention preferably isused neat although it also is contemplated to employ liquid Lewis aciddiluted with up to about 40 vol. % of an inert solvent therefor.Suitable solvents include those materials useful as diluents inpreparation of pretreatment product and supported catalyst component asdescribed hereinabove. Of course, any such solvent should be purifiedprior to use. The amount of Lewis acid used, whether neat or diluted, isnot critical. From a practical standpoint, however, the amount should begreat enough to provide a high degree of contact between the solid andliquid, but not so great as to waste the Lewis acid or requireexcessively large vessels for the contacting. Most preferably, fromabout 3 to about 10 milliliters of Lewis acid are used for each gram ofsolid to be treated.

Temperature in the liquid Lewis acid-contacting step is at least highenough to avoid solidification of the Lewis acid employed, but not sohigh as to adversely affect ultimate catalyst component performance.Preferred temperatures range from about 0° to about 170° C. When TiCl₄is used as the Lewis acid, temperatures of about 20° to about 135° C.are preferred to maintain desirable improvements in catalyticperformance while avoiding waste of TiCl₄ through vaporization thereofand exposure of catalyst components to conditions more severe thannecessary.

The time of contact with liquid Lewis acid is not critical and generallyranges from several minutes to several hours. It is desirable to agitatethe solid and Lewis acid during at least a substantial portion of thistime to ensure a high degree of contact. Preferred contact times rangefrom 1 to about 30 minutes as the same yield the desired improvementswithout occupying preparation equipment for undesirably lengthy periodsof time.

As in preparation of the solid reaction product, the Lewisacid-contacting step according to this invention is conducted in thesubstantial absence of oxygen, water, carbon oxides and extraneouscatalyst poisons. Such materials are excluded by any convenient manneras described hereinabove.

Following contacting with Lewis acid, solids are allowed to settle andsupernatant is removed therefrom such as by filtration or decantation.One or more additional Lewis acid-contacting steps can be carried outwith the same or different Lewis acid. In addition, a series ofalternating Lewis acid and inert liquid hydrocarbon or halogenatedhydrocarbon washes can be conducted if desired.

Prior to use in the polymerization of alpha-olefins, the catalystcomponents used in this invention may be mechanically activated bycomminution. Mechanical activation improves the polymerizationperformance of the invented catalyst components, whether or not treatedwith Lewis acid, in terms of both activity and susceptibility tomodification by crystallinity-promoting modifiers; however, comminutiontypically forms a catalyst component which yields increasednoncrystalline products. The preferred technique for mechanicallyactivating the invented catalyst components is dry ball-milling, thatis, ball-milling in substantial absence of inert diluent. However, goodresults also can be obtained by ball-milling in the presence of a minoramount of an inert diluent such as hexane or another alkane, as well asby other techniques. The above-described catalyst components can becomminuted in the presence of one or more organic electron donors of thegeneral type employed in preparation of the catalyst components.Techniques of comminution by ball-milling generally are known in theart. Typically, titanium-containing catalyst component and hard,nonreactive balls, such as steel or burundum balls, are placed in aclosed container which is agitated, usually by rolling, shaking orrocking. Such comminution is continued for a few hours up to severaldays, typically about 12 to about 36 hours, until the catalyst componentis ground to a desired particle size, typically about 5 to about 50microns. Since mechanical action of comminution can cause a temperatureincrease in the comminuting mixture, care should be taken to keep thetemperature below the decomposition temperature of the catalystcomponent. Typically, the comminuting mixture should be kept below about50° C. Optimum comminution techniques for a specific catalyst componentcan be determined by routine experimentation.

Optimum polymerization performance is attained by treating with Lewisacid and then mechanically activating. Treatment of mechanicallyactivated catalyst component with Lewis acid alone is not preferred asit may result in agglomeration of the component and inferiorpolymerization performance.

Comminuted titanium-containing catalyst component may be retreated bycontact with a halide-containing titanium(IV) compound such as titaniumtetrachloride and at least one alkyl aromatic ester, such as ethylbenzoate or a dialkylphthalate ester, and, optionally, a chlorocarbon,such as carbon tetrachloride, an organochlorosilane or a mixturethereof.

In retreatment of a comminuted supported titanium-containing catalystcomponent according to this invention, a retreatment amount oftitanium(IV) compound is contacted with the comminuted product.Typically, the atomic ratio of retreatment titanium(IV) to titaniumcontained in the comminuted catalyst component is about 50:1 to about500:1 and preferably is about 200:1 to about 250:1. Preferably,retreatment titanium(IV) compound is diluted in a liquid hydrocarbonduring retreatment.

Although the chemical structure of the catalyst components describedherein is not presently known, the components preferably contain fromabout 1 to about 6 wt. % titanium, from about 10 to about 25 wt. %magnesium, less than about 1 wt. % Group IIIA metal and from about 45 toabout 65 wt. % halogen. From the standpoint of attaining maximumefficiency of titanium, catalyst components which are more preferredaccording to this invention contain from about 1.5 to about 3 wt. %titanium, from about 15 to about 20 wt. % magnesium, less than about 0.5wt. % Group IIIA metal, and from about 50 to about 60 wt. % chlorine.

Comminuted catalyst may be prepolymerized with an alpha-olefin beforeuse as a polymerization catalyst component. In prepolymerizationcomminuted catalyst and an organoaluminum compound co-catalyst such astriethylaluminum are contacted with an alpha-olefin such as propyleneunder polymerization conditions, preferably in the presence of amodifier such as methyl p-toluate and in an inert hydrocarbon such ashexane. Typically, the polymer/catalyst weight ratio of the resultingprepolymerized component is about 0.1:1 to about 20:1. Prepolymerizationforms a coat of polymer around catalyst particles which in manyinstances improves particle morphology, activity and stereospecificity.

The above-described catalysts of this invention are useful inpolymerization of alpha-olefins such as ethylene and propylene, and aremost useful in stereospecific polymerization of alpha-olefins containing3 or more carbon atoms such as propylene, butene-1, pentene-1,4-methylpentene-1, and hexene-1, as well as mixtures thereof andmixtures thereof with ethylene. The invented catalysts are particularlyeffective in the stereospecific polymerization of propylene or mixturesthereof with up to about 20 mole % ethylene or a higher alpha-o-lefin.Propylene homopolymerization is most preferred. According to theinvention, highly crystalline polyalphaolefins are prepared bycontacting at least one alpha-o-lefin with the above-described catalystcompositions under polymerizing conditions. Such conditions includepolymerization temperature and time, monomer pressure, avoidance ofcontamination of catalyst, choice of polymerization medium in slurryprocesses, the use of additives to control polymer molecular weights,and other conditions well known to persons of skill in the art. Slurry-,bulk-, and gas-phase polymerization processes are contemplated herein,although gas-phase is preferred.

The amount of catalyst to be employed varies depending on choice ofpolymerization technique, reactor size, monomer to be polymerized, andother factors known to persons of skill in the art, and can bedetermined on the basis of the examples appearing hereinafter.Typically, catalysts of this invention are used in amounts ranging fromone gram of catalyst to about 4000 to about 15,000 grams of polymerproduced, although more or less may be useful.

Irrespective of the polymerization process employed, polymerizationshould be carried out at temperatures sufficiently high to ensurereasonable polymerization rates and avoid unduly long reactor residencetimes, but not so high as to result in the production of unreasonablyhigh levels of stereorandom products due to excessively rapidpolymerization rates. Generally, temperatures range from about 0° toabout 120° C. with about 20° to about 95° C. being preferred from thestandpoint of attaining good catalyst performance and high productionrates. More preferably, polymerization according to this invention iscarried out at temperatures ranging from about 50° to about 80° C.

Alpha-olefin polymerization according to this invention is carried outat monomer pressures of about atmospheric or above. Generally, monomerpressures range from about 20 to about 600 psi, although in vapor phasepolymerizations, monomer pressures should not be below the vaporpressure at the polymerization temperature of the alpha-olefin to bepolymerized.

The polymerization time will generally range from about 1/2 to severalhours in batch processes with corresponding average residence times incontinuous processes. Polymerization times ranging from about 1 to about4 hours are typical in autoclave-type reactions. In slurry processes,the polymerization time can be regulated as desired. Polymerizationtimes ranging from about 1/2 to several hours are generally sufficientin continuous slurry processes.

Diluents suitable for use in slurry polymerization processes includealkanes and cycloalkanes such as pentane, hexane, heptane, n-octane,isooctane, cyclohexane, and methylcyclohexane; alkylaromatics such astoluene, xylene, ethylbenzene, isopropylbenzene, ethyl toluene,n-propyl-benzene, diethylbenzenes, and mono- and dialkylnaphthalenes;halogenated and hydrogenated aromatics such as chlorobenzene,chloronaphthalene, ortho-dichlorobenzene, tetrahydronaphthalene,decahydronaphthalene; high molecular weight liquid paraffins or mixturesthereof, and other well-known diluents. It often is desirable to purifythe polymerization medium prior to use, such as by distillation,percolation through molecular sieves, contacting with a compound such asan alkylaluminum compound capable of removing trace impurities, or byother suitable means.

Examples of gas-phase polymerization processes in which the catalyst ofthis invention is useful include both stirred bed reactors and fluidizedbed reactor systems are described in U.S. Pat. Nos. 3,957,448,3,965,083, 3,971,768, 3,970,611, 4,129,701, 4,101,289; 3,652,527 and4,003,712 all incorporated by reference herein. Typical gas phase olefinpolymerization reactor systems comprise a reactor vessel to which olefinmonomer and catalyst components can be added and which contain anagitated bed of forming polymer particles. Typically, catalystcomponents are added together or separately through one or morevalve-controlled ports in the reactor vessel. Olefin monomer, typically,is provided to the reactor through a recycle gas system in whichunreacted monomer removed as off-gas and fresh feed monomer are mixedand injected into the reactor vessel. A quench liquid which can beliquid monomer, can be added to polymerizing olefin through the recyclegas system in order to control temperature.

Irrespective of polymerization technique, polymerization is carried outunder conditions that exclude oxygen, water, and other materials thatact as catalyst poisons. Typically, no special precautions need be takento exclude such materials because a positive pressure of monomer gascommonly exists within the reactor.

Also, according to this invention, polymerization can be carried out inthe presence of additives to control polymer molecular weights. Hydrogenis typically employed for this purpose in a manner well known to personsof skill in the art.

Although not usually required, upon completion of polymerization, orwhen it is desired to terminate polymerization or deactivate thecatalysts of this invention, the catalyst can be contacted with water,alcohols, acetone, or other suitable catalyst deactivators in a mannerknown to persons of skill in the art.

The products produced in accordance with the process of this inventionare normally solid, predominantly isotactic polyalpha-olefins. Polymeryields are sufficiently high relative to the amount of catalyst employedso that useful products can be obtained without separation of catalystresidues. Further, levels of stereorandom by-products are sufficientlylow so that useful products can be obtained without separation thereof.The polymeric products produced in the presence of the inventedcatalysts can be fabricated into useful articles by extrusion, injectionmolding, and other common techniques.

Irrespective of the invention claimed herein, examples of possiblechloride-containing co-catalyst compositions are based upon atrialkylaluminum such as triethylaluminum, a source of Al--Cl groups andan organo electron donor such as an organic ester. In this use, examplesof trialkylaluminum species include RR'R"Al wherein R,R' and R" arealkyl groups containing 2 to about 6 carbon atoms such astriethylaluminum, tripropylaluminum or tributylaluminum. Examples ofsources of Al--Cl groups include AlCl₃, alkylaluminum dichloride such asethylaluminum dichloride and dialkylaluminum chlorides such asdiethylaluminum dichloride and diisobutylaluminum chloride. Typicalorganic esters include ethyl benzoate, ethyl-p-anisate, methylp-anisate, methyl p-toluate and dialkylphthalate esters such asdiisobutylphthalate. In such three-component chloride-containingsystems, aluminum/ester and Cl/ester molar ratios are important toobtain good performance. For example, best stereospecificity typicallyis obtained in gas phase or bulk polymerization with 1.0≧Cl/ester≧3.0and 3≦Al/ester≦2, while in slurry phase the best conditions are in themolar ratio range Al/Cl/ester =3-8/2-5/1 and Al/Ti =50-200. If achloride-containing co-catalyst component is not troublesome,diisobutylaluminum hydride combined with a secondary amine, such aspiperidine and/or dicyclohexylamine, and a chloride-containingalkylaluminum compound such as diethylaluminum chloride can be used.Other co-catalyst compositions include reaction products ofdialkylaluminum hydride, such as diethylaluminum hydride, and hinderedamine including tetraalkyl piperidines such as2,2',6,6'-tetramethylpiperidine. The reaction product of diethylaluminumhydride and 2,2',6,6'-tetramethylpiperidine is a white crystalline solididentified as ethyl (2,2',6,6'-tetramethylpiperidine) aluminum hydride.Such co-catalysts may be used in conjunction with trialkylaluminum, suchas triethylaluminum, and dialkylaluminum halides, such asdialkylaluminum chloride. A hindered amine such as2,2',6,6'-tetramethylpiperidine sometimes is useful in a cocatalystcomposition to improve supported catalyst feeding and to reduce finesand lumps in the polymer powder produced. Supported catalysts may becombined with a mixture or trialkylaluminum or alkylaluminum halide suchas diethylaluminum chloride and an ester such as methyl p-toluate beforeaddition to the reactor. Silyl halides such as ethyl trichlorosilane,silicon tetrachloride, trimethylchlorosilane and dimethyldichlorosilanesometimes are useful in cocatalyst systems. Other silane compounds alsocan be useful in cocatalyst compositions such as alkyl, alkoxy and/oraromatic substituted silanes including phenyltriethoxysilane,diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilaneand phenytriisobutylsilane.

The following examples demonstrate but do not limit the describedinvention.

EXAMPLES AND COMPARATIVE RUNS PREPARATION OF TITANIUM-CONTAININGCOMPONENT Step A: Preparation of Pretreated Magnesium-containingComponent

Into a one-liter flask equipped with magnetic stirrer and maintainedunder nitrogen in a drybox were added 200 milliliters of dry n-hexaneand 25.0 grams of anhydrous magnesium ethoxide (obtained from DynamitNobel) at ambient temperature. The resulting suspension was stirred and25 milliliters of a mixture of a 25 wt. % solution of triethylaluminum(TEA) in dry n-hexane was added. Stirring was continued for one hourfollowing completion of the addition of TEA solution and then the solidreaction product was allowed to settle. The supernatant then wasdecanted and the solid was washed eight times with 100-milliliterportions of dry n-hexane and then dried under a stream of nitrogen gasfor about 20 minutes.

Step B: Preparation of Supported Catalyst Component

The solid from Step A was resuspended in a one-liter resin kettleequipped with an overhead stirrer in 50 milliliters of carbontetrachloride, 50 milliliters of 1,2-dichloroethane and 100 millilitersof titanium tetrachloride at ambient temperature. To the resultingmixture, six milliliters of ethyl benzoate were added dropwise over aperiod of about 3 minutes at ambient temperature with stirring at 500rpm. After addition of the ester was completed, the resulting mixturewas heated to 90° to 95° C., stirred at this temperature for 1.75 hours,and then allowed to cool. The supernatant then was decanted, about 150milliliters of dry n-hexane were added, and the solid was separated fromthe liquid by filtration and dried.

Step C: Comminution of Supported Catalyst Component

The solid catalyst component prepared in Step B and 70 stainless steelballs having a diameter of 10 millimeters were placed in a Roalox,burundum-fortified porcelain mill jar (manufactured by A. DaiggerCompany) having a capacity of 1/4 quart (about 280 milliliters) andmilled in a rotary ball mill (manufactured by Paul O. Abbe, Inc.,rolling speed=120 rpm) for 16 hours at ambient temperature under anatmosphere of dry nitrogen. The solid was sieved to remove all particleswhich could not pass through a 200 mesh (U.S. Sieve Series) sieve.

Step D: Retreatment of Comminuted Catalyst Component

The solid obtained from Step C was mixed with equal portions of1,2-dichloroethane and of carbon tetrachloride (each at 2-3 ml/gram ofsolid) and an excess of titanium tetrachloride (6-7 ml/gram of solid)was added. After 0.02-0.03 milliliter of ethylbenzoate per milliliter oftitanium tetrachloride was added dropwise to this mixture with stirringat 400-500 rpm, the resulting suspension was heated to 95°-100° C. for1.5 hours while stirring. After cooling to 80° C., the solid product wasallowed to settle, supernatant liquid was removed by decantation and theresidue washed five times with 150-milliliter portions of n-hexane. Theremaining solid was filtered and dried.

Examples I-VII

A series of propylene polymerization runs was performed in a laboratoryscale continuous unit based on that described in U.S. Pat. No.3,965,083. A cylindrical reactor vessel of approximately four inches indiameter and 12 inches in length was equipped with three recycle gasnozzles spaced equidistantly along the bottom of the reactor and threeliquid quench nozzles spaced equidistantly along the top of the reactor.The reactor was equipped with an off-gas port for recycling reactor gasthrough a condenser and back through a recycle gas line to the recyclegas nozzles in the reactor. During operation polypropylene powder wasproduced in the reactor bed, flowed over a weir, and discharged though apowder discharge system into a secondary closed vessel blanketed withnitrogen. Polymerization temperature and pressure was maintained at 160°F. and 300 psig respectively. The polymer bed was agitated by paddlesattached to a longitudinal shaft with in the reactor rotating at about40 rpm. Hydrogen content in the recycle gas was maintained at 2-4%.Except where noted, titanium-containing catalyst component wasintroduced into the reactor through a liquid propylene-flushed catalystaddition nozzle. A separate addition sequence is used to add mixedco-catalyst, chilled to 30° F. through a co-catalyst addition nozzle.Activity was determined by dividing Yield measured by magnesium atomicabsorption analysis by residence time.

In this series of polymerizations, piperidine (PiP),2,6-dimethylpiperidine (DMPiP) and 2,2',6,6'-tetramethylpiperidine(TMPiP) were used in the cocatalyst system with various ratios oftriisobutylaluminum (TIBA) and methyl p-toluate (MpT). A comparison runusing diethylaluminum chloride (DEAC) also is shown. Results arepresented in Table I.

Comparative Runs were performed demonstrating the special usefulness ofthe catalyst of this invention in gas-phase polymerization with respectto bulk and slurry polymerizations. Bulk propylene polymerizations wereconducted using aliquots of titanium-containing catalyst componentsprepared above. Portions of aluminum alkyl and co-catalyst and 10milligrams of titanium-containing catalyst component were combined in adrybox under nitrogen and flushed into a two-liter Parr reactor in 300milliliters of propylene. After an additional 1000 milliliters ofpropylene and 42 millimoles of hydrogen were charged to the reactor, thereactor was closed and polymerization conducted at 160° F. for twohours. After the reactor was cooled and vented, the resulting solidpolymer was air dried overnight and then weighed. Slurry polymerizationswere conducted in 780 milliliters of n-hexane contained in a 2-literautoclave equipped with a mechanical stirrer. Polymerization wascontinued for two hours at 160° F. at 250 psig using 30 milligrams ofcatalyst, after which time solid polypropylene was removed from thereactor, filtered, dried and weighed. Gas-phase polymerizations wereperformed as described above. Results are shown in Table II. The amountof "Extractables" was determined by measuring the loss in weight of adry sample of ground polymer after being extracted in boiling n-hexanefor six hours. Hexane "Solubles" were determined by evaporation of thefiltrate to dryness and weighing the residue.

Active Chloride is measured as the amount of hydrogen chloride gasevolved while passing a stream of nitrogen over a molten polypropylenesample at 300° C. in parts per million by weight (ppm). Typically,"active chloride" determinations are run in duplicate or triplicate witheach measurement reported individually.

The data in Table I show generally that in gas phase polymerization aco-catalyst formulation based on piperidine is preferred over a similarformulation based on tetramethylpiperidine. Run J is presented to show atypical co-catalyst system yielding high "active chloride" levels.Examples of this invention approach the activity-stereospecificityperformance of such a catalyst producing substantial amounts of "activechloride." Table II clearly shows the advantage of the catalysts of thisinvention when used in gas-phase propylene polymerization.

                  TABLE I                                                         ______________________________________                                        Ex-                               Acti-  Extrac-                              ample                       Yield vity   tables                               (Run) R.sub.2 NH    Al/Ti   (g/g) (g/g/hr)                                                                             (wt %)                               ______________________________________                                                       TIBA/                                                                         MpT/                                                                          R.sub.2 NH                                                     A     TMPiP    2.75/1/1 292   5600  2100   1.9                                B     TMPiP    3.0/1/1  294   5800  2300   2.5                                C     TMPiP    3.25/1/1 258   5600  2700   2.5                                D     TMPiP    3.75/1/1 259   7400  3500   2.8                                E     TMPiP    4.25/1/1 259   8200  4100   3.3                                F     TMPiP    4.25/1/1 259   7800  3900   3.4                                G     TMPiP    4.25/1/1 293   8000  4000   3.4                                H     DMPiP    4.25/1/1 259   6000  2600   4.3                                I     PiP      4.25/1/1 293   9200  5400   3.9                                II    PiP      4.25/1/1 293   12000 7100   .sup. 4.7.sup.1                    III   PiP      4.25/1/2 290   5100  2200   .sup. 3.3.sup.2                    IV    PiP      4.25/1/2 290   6000  3200   .sup. 2.9.sup.3                    V     PiP      3.75/1/1 292   5200  2600   2.6                                VI    PiP      4.25/1/1 259   10600 1.7    4.3                                               TIBA/                                                                         DEAC/                                                                         MpT                                                            J     --       2.25/    347   10400 6900   .sup. 2.7.sup.4                                   2.5/1                                                          ______________________________________                                         .sup.1 Active chloride in airkilled powder = 0,0                              .sup.2 Precipitate formed upon chilling of cocatalyst; mixture was warmed     to ambient temperature before use.                                            .sup.3 Cocatalyst mixture aged 12 hours.                                      .sup.4 Active chloride in airkilled powder = >126,147,86                 

                                      TABLE II                                    __________________________________________________________________________                            Acti-                                                                              Extrac-                                                                           Sol-                                         Example      TIBA/MpT/                                                                            Yield                                                                             vity tables                                                                            ubles                                        (Run)                                                                              Type.sup.1                                                                        R.sub.2 NH                                                                        R.sub.2 NH                                                                           (g/g)                                                                             (g/g/hr)                                                                           (wt %)                                                                            (wt %)                                       __________________________________________________________________________    K    Slry                                                                              TMPiP                                                                             4.0/1/1                                                                              8515                                                                              4300 1.0 2.7                                          M    Bulk                                                                              TMPiP                                                                             4.25/1/1                                                                             12200                                                                             6100 2.9 --                                           VII  G-P TMPiP                                                                             4.25/1/1                                                                             8000                                                                              4000 3.4 --                                           N    Slry                                                                              PiP 4.0/1/1                                                                               775                                                                               400 --  2.6                                          P    Bulk                                                                              PiP 4.25/1/1                                                                             6400                                                                              3200 1.9 --                                           VIII G-P PiP 4.25/1/1                                                                             12000                                                                             7100 4.7 --                                           __________________________________________________________________________     .sup.1 G-P = gasphase;                                                        Slry = slurry                                                            

Examples IX-XV

A series of propylene polymerizations was run similar to that describedin Example I using a co-catalyst component containing a reaction productof a dialkylaluminumhydride and a secondary amine. In these examples,42.6 grams (0.3 mole) of diisobutylaluminumhydride were added to 150milliliters of hexane. To this mixture 30.0 milliliters of piperidinewere added slowly over 1.5 hours accompanied by gas evolution andheating of the reaction solution. After piperidine addition, sufficienthexane was added to produce 300 milliliters total volume. The resultingmixture, 1.0 Molar in aluminum components, was used as a co-catalystcomponent in propylene polymerization as described in Example I. Theresults of these polymerizations including comparative runs usingco-catalyst components prepared similarly but incorporatingtetramethylpiperidine or diethylaluminum chloride are shown in TableIII. Co-catalyst mixture was maintained at ambient temperature except asnoted. The data contained in Table III show that, at comparableconditions in gas-phase polymerization, use of piperidine in theco-catalyst composition show significant improvement in extractablescontent compared to use of 2,2,6,6-tetramethylpiperidine. Additionally,powder produced from polymerizations not using diethylaluminum chlorideshow a lower active chloride level and a higher flexural modulus thanmeasured in Run U in which DEAC is used.

                  TABLE III                                                       ______________________________________                                        Ex-                                Acti- Extrac-                              ample                 Al/    Yield vity  tables                               (Run) R.sub.2 NH      Ti     (g/g) (g/g/hr)                                                                            (wt %)                               ______________________________________                                                      TIBA/MpT/                                                                     DIBAG.R.sub.2 NH                                                Q     TMPiP   2.25/1/1    158  5200  1800  2.5                                R     TMPiP   2.75/1/1    128  9200  5400  3.7                                S     TMPiP   3.0/1/1     154  8200  5500  3.6                                T     TMPiP   3.0/1/1     154  10400 5200  4.3                                IX    PiP     3.0/1/1     154  8200  4800  2.6                                X     PiP     3.0/1/1     154  8200  4600  .sup.  2.3.sup.1,3                 XI    PiP     3.25/1/1    158  8200  4600  2.2                                XII   PiP     3.25/1/1    158  7800  4300  .sup. 2.2.sup.1                    XIII  PiP     3.0/1/1.5   159  7800  4300  2.3                                XIV   PiP     3.0/1/1.5   159  8700  4100  2.3                                              TIBA/TEA/                                                                     MpT/                                                                          DIBAH.R.sub.2 NH                                                XV    PiP     2.0/1/1/1   154  8700  4600  .sup. 1.8.sup.2                                  TIBA/DEAC/                                                                    MpT                                                             U     --      2.25/2.5/1  347  10400 6900  .sup.  2.7.sup.2,4                 ______________________________________                                         .sup.1 Cocatalyst aged 30 hours.                                              .sup.2 Cocatalyst chilled to -30° F.                                   .sup.3 Active chloride = 0,0;                                                 Flexural modulus = 233,000 psi                                                .sup.4 Active chloride = 147,86,>126;                                         Flexural modulus = 217,000 psi                                           

Examples XVI-XXIV

A series of propylene polymerizations was run similar to that describedin Example I using a different batch of titanium-containing component.The co-catalyst used in these examples was a reaction product ofdiisobutyl aluminum hydride and an unhindered secondary amine includingpiperidine (PiP) and di-n-propylamine (DNPA). A mixture of triethylaluminum (TEA) and triisobutyl aluminum (TIBA) was used together withmethyl p-toluate (MpT). Results are shown in Table IV. Comparative Run Wwithout an amine product also is shown.

                  TABLE IV                                                        ______________________________________                                                                           Acti-                                      Ex-                                vity  Extrac-                              ample Temp            Al/    Yield (g/g/ tables                               (Run) (°F.)    Ti     (g/g) hr)   (wt %)                               ______________________________________                                                      TIBA/TEA/                                                                     MpT                                                                           DIBAH.PiP                                                       W     150     1.5/1.5/1/0 301  8600  5100  4.3                                XVI   160     1/4/1/4/1/1 288  4400  1700  2.7                                XVII  160     1.5/1.5/1/1 301  6800  3100  3.2                                XVIII 170     1.5/1.5/1/1 301  6300  2600  2.4                                XIX   150     1.5/1.5/1/1 301  8600  5100  3.4                                XX    160     2.0/1/1/1   301  6800  3800  3.5                                              TIBA/TEA/                                                                     MpT                                                                           DIBH.DNPA                                                       XXI   160     2.0/1/1/1   301  6300  3300  3.8                                XXII  160     2.0/1/1/2   302  5900  3100  6.0                                XXIII 160     2.25/1/1/1  316  5900  2800  4.1                                XXIV  160     2.0/1/1/1   309  8700  4600  2.7                                ______________________________________                                    

Examples XXV

Another series of propylene polymerizations was run similar to thatdescribed in Example I using another different batch oftitanium-containing component. The co-catalyst used in these exampleswas a reaction product of a dialkylaluminum hydride and a secondaryamine such as piperidine (PiP) and dicyclohexylamine (DCHXA). Thetrialkyl aluminum component was a 1:1 mixture of triethyl aluminum (TEA)and triisobutyl aluminum (TIBA). Methyl p-toluate (MpT), methyl anisate(MA) or ethyl anisate (EA) was included. Results are shown in Table V.

                                      TABLE V                                     __________________________________________________________________________                                     Extrac-                                      Example                                                                             Temp              Yield                                                                             Activity                                                                           tables                                       (Run) (°F.)  Al/Ti                                                                             (g/g)                                                                             (g/g/hr)                                                                           (wt %)                                       __________________________________________________________________________              TIBA/TEA/MpT/                                                                 DIBAH.PiP                                                           XXV   150 1.55/1.55/1/1                                                                           284 10800                                                                             7700 4.6                                          XXVI  150 1.55/1.55/1/1                                                                           284 9500                                                                              6800 3.3                                          XXVII 150 1.4/1.4/1/1                                                                             280 5200                                                                              2300 3.2                                          XXVIII                                                                              150 1.4/1.4/1/1                                                                             280 4600                                                                              2000 2.4                                          XXIX  160 1.55/1.55/1/1                                                                           284 7000                                                                              3300 3.6                                          XXX   160 1.55/1.55/1/1                                                                           284 9500                                                                              4500 4.6                                          XXXI  160 2.0/2.0/1/1                                                                             282 9500                                                                              6300 3.7                                          XXXII 160 2.0/2.0/1/1                                                                             282 9500                                                                              6300 3.9                                                    TIBA/TEA/MA/                                                                  DIBAH.PiP                                                           XXXIII                                                                              160 2.5/1/1/1 312 8100                                                                              4100 3.8                                          XXXIV 160 2.5/1/1/1 312 7000                                                                              3500 3.4                                          XXXV  160 2.75/1/1/1                                                                              327 9000                                                                              5000 4.6                                          XXXVI 160 2.75/1/1/1                                                                              327 9000                                                                              5000 5.2                                          XXXVII                                                                              150 2.5/1/1/1 312 9000                                                                              5600 3.4                                          XXXVIII                                                                             150 2.5/1/1/1 312 8100                                                                              5100 2.6                                          XXXIX 150 2.75/1/1/1                                                                              327 9000                                                                              5000 3.0                                          XL    150 2.75/1/1/1                                                                              327 9000                                                                              5000 3.5                                                    TIBA/TEA/MpT/                                                                 DIBAH.DCHXA                                                         XLI   160 2.0/1/1/1 282 8500                                                                               5000                                                                              3.8                                          XLII  160 2.0/1/1/1 282 10100                                                                             5000 4.5                                          XLIII 150 2.0/1/1/1 282 10800                                                                             7200 3.5                                          XLIV  150 2.0/1/1/1 282 10800                                                                             7200 3.5                                          XLV   150 2.5/1/1/1 312 14700                                                                             11300                                                                              4.7                                          XLVI  150 2.5/1/1/1 312 12500                                                                             9600 4.8                                          XLVII 150 2.25/1/1/1                                                                              297 10100                                                                             6300 4.4                                          XLVIII                                                                              150 2.25/1/1/1                                                                              297 10100                                                                             6300 4.4                                          XLIX  150 2.0/1/1/1 282 9500                                                                              5900 4.0                                          L     150 2.0/1/1/1 282 9500                                                                              5900 3.5                                          LI    150 1.75/1/1/1                                                                              268 9500                                                                              5300 3.4                                          LII   150 1.75/1/1/1                                                                              268 9500                                                                              5300 3.2                                                    TIBA/TEA/EA/                                                                  DIBAH.DCHXA                                                         LIII  150 2.0/1/1/1 282 9500                                                                              5900 4.0                                          LIV   150 2.0/1/1/1 282 9000                                                                              5600 4.3                                          LV    150 2.25/1/1/1                                                                              297 9500                                                                              5900 4.3                                          LVI   150 2.25/1/1/1                                                                              297 9500                                                                              5900 4.4                                          __________________________________________________________________________

What is claimed is:
 1. A catalyst system suitable for gas-phasepolymerization of alpha-olefins to polymers containing essentially noactive chloride comprising:A. a titanium-containing component supportedon a hydrocarbon-insoluble magnesium-containing compound in combinationwith an electron donor compound; and B. a co-catalyst comprising (a) atleast one trialkyl aluminum compound, (b) an aromatic acid ester, and(c) an unhindered secondary amine, such secondary amine having no morethan one methyl group on a carbon atom adjacent to a nitrogen atom,optionally reacted with a dialkylaluminum hydride, in substantialabsence of compounds containing an Al--Cl bond.
 2. The catalyst of claim1 wherein the unhindered secondary amine contains alkyl groups havingfrom two to about eight carbon atoms or is a cyclic aliphatic secondaryamine containing from four to about ten carbon atoms.
 3. The catalyst ofclaim 1 wherein the unhindered amine is piperidine, 2-methylpiperidine,pyrrolidine, homopiperidine, piperazine, dicyclohexylamine ordi-n-propylamine.
 4. The catalyst of claim 1 wherein the unhinderedamine is piperidine, pyrrolidine, homopiperidine or piperazine.
 5. Thecatalyst of claim 1 wherein the unhindered amine is piperidine.
 6. Thecatalyst of claim 1 wherein the trialkyl aluminum is triethylaluminum,triisobutylaluminum or a combination thereof.
 7. The catalyst of claim 1wherein the trialkyl aluminum is triisobutylaluminum.
 8. The catalyst ofclaim 1 wherein the unhindered secondary amine is complexed with adialkylaluminum hydride in which the alkyl groups contain from aboutfour to about six carbon atoms.
 9. The catalyst of claim 1 wherein thearomatic acid ester contained in the cocatalyst is ethylbenzoate, ethylanisate, methyl p-toluate or methyl p-anisate.
 10. The catalyst of claim9 wherein the aromatic acid ester is methyl p-toluate.
 11. The catalystof claim 1 wherein the titanium-containing component is formed byreacting a titanium tetrahalide with a magnesium alcoholate.
 12. Thecatalyst of claim 1 wherein the titanium-containing componenet is formedby reacting a titanium tetrahalide with a magnesium halide.
 13. Thecatalyst of claim 1 wherein the electron donor is at least one aromaticacid ester.
 14. A catalyst system suitable for gas-phase polymerizationof alpha-olefins to polymers containing essentially no active chloridecomprising.A. a titanium-containing component supported on ahydrocarbon-insoluble magnesium-containing compound in combination withan aromatic acid ester; and B. a co-catalyst comprising (a)triethylaluminum, triisobutylaluminum or a combination thereof, (b) anaromatic acid ester selected from the group consisting of ethylbenzoate,ethylanisate, methyl p-anisate and methyl p-toluate, and (c) a cyclicunhindered secondary amine, such secondary amine having no more than onemethyl group on a carbon atom adjacent to a nitrogen atom, containingfrom four to about 10 carbon atoms, optionally reacted with adialkylaluminum hydride, in substantial absence of compounds containingan Al--Cl bond.
 15. The catalyst of claim 14 wherein thetrialkylaluminum is triisobutylaluminum.
 16. The catalyst of claim 15wherein the aromatic acid ester is methyl p-toluate.
 17. The catalyst ofclaim 15 wherein the cyclic secondary amine is piperidine.
 18. Thecatalyst of claim 16 wherein amine is piperidine.
 19. The catalyst ofclaim 17 wherein the cyclic secondary amine is complexed with anapproximately equivalent amount of diisobutylaluminum hydride.